Synthesis of ordered mesoporous carbon molecular sieve and its adsorption capacity for H2, N2, O2, CH4 and CO2

Article abstract of DOI:10.1016/j.cplett.2005.07.048

Ordered mesoporous carbon is a recently developed material. To test its potential application for adsorption, such a material was synthesized using silica SBA-15 as the template and sucrose as the carbon source. The ordered structure and the mesopore dimension of the material were proven with XRD, SEM and TEM examinations. Adsorption data of H₂, N₂, O ₂, CH₄ and CO₂ on the ordered mesoporous carbon were collected with a typical volumetric method for a pressure range up to 11 MPa. Potential application for the separation of CO₂-CH ₄-air mixture was indicated.

Full text of DOI:10.1016/j.cplett.2005.07.048

Chemical Physics Letters 413 (2005) 6–9
www.elsevier.com/locate/cplett
Synthesis of ordered mesoporous carbon molecular sieve and
its adsorption capacity for H , N , O , CH and CO
2
2
2
4
2
a,
a
a
a
b
b
*
Li Zhou , Xiuwu Liu , Jingwen Li , Ning Wang , Zhen Wang , Yaping Zhou
a
High Pressure Adsorption Laboratory (State Key Laboratory of Chemical Engineering), School of Chemical Engineering and Technology,
2 Weijin Road, Nankai District, Tianjin University, Tianjin 300072, China
9
Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
b
Received 1 June 2005; in final form 13 July 2005
Available online 8 August 2005
Abstract
Ordered mesoporous carbon is a recently developed material. To test its potential application for adsorption, such a material was
synthesized using silica SBA-15 as the template and sucrose as the carbon source. The ordered structure and the mesopore dimen-
sion of the material were proven with XRD, SEM and TEM examinations. Adsorption data of H
ordered mesoporous carbon were collected with a typical volumetric method for a pressure range up to 11 MPa. Potential applica-
tion for the separation of CO –CH –air mixture was indicated.
Ó 2005 Elsevier B.V. All rights reserved.
2 2 2 4 2
, N , O , CH and CO on the
2
4
1
. Introduction
meric alky-ethylene oxide surfactant (Pluronic P123)
was used as the structure-directing agent and tetraethyl
orthosilicate (TEOS) of analysis grade was used as the sil-
ica source. After filtration and drying, the as-synthesized
product was calcinated at 823 K to obtain the SBA-15
structure. Using SBA-15 as the template and sucrose as
the carbon source, the carbon replica was produced.
The quantity ratio of sucrose to the silica SBA-15 (C/Si)
was kept at 1.25. The as-synthesized product was heated
in vacuum to 1173 K with a heating rate of 5 K/min to
complete the carbonization of sucrose. The silica template
was washed out with 1 M NaOH (in solution of 50% eth-
anol in water) at temperature 373 K. The template-free
carbon product thus obtained was filtered, washed with
ethanol, and dried at 393 K. The carbon material ob-
tained was indeed CMK-3-1.25 according to the conven-
tional nomination rule and the initial C/Si ratio.
Ordered mesoporous material has been recently devel-
oped [1–3]. This kind of material attracted much research
interest on its potential application due to the favorable
property: the large pore volume, high specific surface
area, high thermal stability, high stability in strong acids
and bases, high mechanical stability, chemical inertness,
solidity, and the ordered mesopore structure [4–10]. To
further test the potential usage of the material for
adsorptive storage of hydrogen and methane, and for
the separation of gas mixtures, especially those of air
with carbon dioxide and methane, based on adsorption,
such a material was synthesized, and adsorption iso-
therms of hydrogen, nitrogen, oxygen, methane and car-
bon dioxide on the material were collected.
The synthesized carbon material was examined by
small angle X-ray diffraction (XRD), scanning electron
microscope (SEM), transmission electron microscope
2
. Experiment
SBA-15 silica with 2-dimensional ordered channels
(TEM) and the adsorption of nitrogen at 77 K, from
was synthesized in acidic condition. A non-ionic oligo-
which the specific surface area, pore volume and pore
size distribution was determined based on the BET
[11] and BJH [12] theory.
*
Corresponding author. Fax: +86 22 8789 1466.
E-mail address: zhouli-tju@eyou.com (L. Zhou).
0
009-2614/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.cplett.2005.07.048

L. Zhou et al. / Chemical Physics Letters 413 (2005) 6–9
7
The adsorption isotherms of the testing gases on the
synthesized material were collected on a typical volu-
metric apparatus adapted for high-pressure adsorption
studies. Working principle and details of the apparatus
were previously presented [13]. Sample was first dried
at 300 °C for 12 h in a vacuum oven. All gases used
are of purity above 99.99%. Pressure was measured with
sensitivity of 0.05% up to 11 MPa. Temperature was
kept constant within ± 0.1 °C.
micropores connecting the cylindrical channels in the
SBA-15 templates, the carbon nanorods are intercon-
nected due to the micropore filling of the silica template
with carbon source. The peak indicating the existence of
the reflection (1 0 0) is clearly identified in the XRD
spectrum, which is in agreement with the hexagonal or-
2
dered structure. The BET surface area is 1098 m /g and
3
the total pore volume is 1.30 cm /g based on nitrogen
adsorption data. Pore size distribution of CMK-3-1.25,
determined on treating the nitrogen data at 77 K with
the BJH theory, is shown in Fig. 3. It is shown that
the synthesized carbon material is mesoporous with
quite narrow pore-size distribution centered at 3.8 nm,
which is consistent with the results of TEM and XRD
analysis.
To test the storage capacity of the material for hydro-
gen, an adsorption isotherm was collected at 273 K. As
shown in Fig. 4, the isotherm shows the type-I feature
and the highest capacity is less than 0.5% at 10 MPa
and 273 K. This is reasonable because the adsorption
3
. Results and analyses
The ordered structure of the synthesized carbon
material is clearly shown in the SEM and TEM photos
of Figs. 1 and 2. Since the template, SBA-15, consists
of channels in hexagonal arrangement, its inverse rep-
lica, carbon CMK-3-1.25, consists of hexagonally ar-
ranged nanorods. The TEM analysis reports that the
nanorods are 9.6-nm apart. Because there are some
Fig. 1. SEM photo of the synthesized carbon material in two scales.
Fig. 2. TEM photos of the synthesized carbon material taken along the nanorod direction and the direction perpendicular to it (the circular black
dots are nanorods).

8
L. Zhou et al. / Chemical Physics Letters 413 (2005) 6–9
3
2
2
1
1
.0
.5
.0
.5
.0
CO2
1
0.0
298 K
7
.5
.0
.5
.0
5
2
0
CH4
n
P
S
D
O2
N2
.
5
0
.0
0
0
.0
.5
1.0 1.5
2.0
1.5
3.0
3.5
.0
2.5
5.0
7.5
10.0 12.5 15.0 17.5
p/MPa
Pore size/nm
Fig. 5. Adsorption isotherms of N
2
, O
2
, CH
4
2
and CO at 298 K.
Fig. 3. Pore size distribution of the synthesized carbon material.
4
. Conclusion
.
.
.
.
.
5
4
3
2
1
An ordered mesoporous molecular sieve consists of
hexagonally arranged carbon nanorods was synthesized
with a template technique. It has a specific surface area
2
3
of about 1100 m /g and pore volume of 1.30 cm /g cen-
tered at 3.8 nm. Although it is not suitable for hydrogen
storage, it shows preferable adsorption affinity for CO2
than for methane, oxygen and nitrogen; therefore, it
might have potential application for the important sep-
n
aration task of CO -containing gas mixtures.
2
Acknowledgement
2
73 K
The financial support of the National Natural Science
Foundation of China (Grant No. 20336020) is gratefully
acknowledged.
0
.0
0.0
1.5
3.0
4.5
6.0
7.5
9.0 10.5 12.0
p/MPa
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Fig. 4. Adsorption isotherm of H at 273 K.
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